research and development
by Kiyoshi Kitana
Summary: Hanji enlists Armin and Eren's help in testing a theory of hers; the side effects are unexpected. [notes inside][eremin]
1. Chapter 1

**Notes:** This first part actually stands alone on its own and is only Eremin. The second part is solo!Hanji and is posted as a second chapter for those who are also interested in that part. Also, warning for altered mental states.

* * *

"Thank you again for volunteering for this, Armin," Hanji says to him amicably, leading the teen through twisting corridors. The pages of her clipboard flutter with the swing of her arms as they walk.

Armin shakes his head in response, dismissing her thanks. "No, I'm happy to be a part of your experiment. It's important that we learn as much as we can about Titan shifters."

About Eren, he thinks, but decides not to share that part. Two days ago, Armin had been approached by the bouncy scientist, requesting his assistance in testing a theory she had. It could barely be called a theory, half fleshed out with gaping holes, but in essence, Armin understood what she was getting at.

"Do you really believe there aren't any significant differences between normal humans and Titan shifters, though?" Armin asks as they get closer to their destination.

Hanji shoots him a bright smile and winks at him. "That's what we're here to find out."

The room Hanji chooses is sparse, with a desk, bed, and three chairs. Eren is already in the room, sprawled out on the bed, when they arrive. He is barefoot, clad in his casual shirt and uniform pants. Eren sits up and says, yawning, "What took you so long? I almost fell asleep waiting."

Hanji just continues smiling and says, "Sorry about that." Then, she turns to Armin and gestures. "And Armin, why don't you have a seat?"

So the blonde does, kicking off his shoes and taking up residence on a corner of the bed Eren is on. He looks over at Eren and, when Eren catches his gaze, gives him a small smile. Eren returns it, then turns his attention to Hanji when she has a sudden outburst of "There it is!"

Hanji pulls out two small glass vials from one of her many pockets. The vials are clear and hold a liquid of a deep blue hue. She steps in front of the two teens and holds out a vial to each of them. "One for you, and," she says in Eren's direction, and then Armin, "one for you. Drink up!"

Armin holds the vial between his index finger and thumb, peering at it closely. "It looks weird," he can't help but say. He feels a brief pang of uncertainty and takes a deep breath to steady himself.

"Yeah, it does," Eren adds, sounding perplexed as he looks between the vial in his palm, Hanji, and Armin. He catches Armin's look of uncertainty and reaches over to clasp the blonde's shoulder reassuringly. "Don't worry; we're doing this together, remember?"

Armin nods and makes a noise of affirmation. He pops the top of the vial and tosses the liquid to the back of his throat as fast as he can, trying to avoid any unpleasant tastes. Eren does the same shortly after and says, "Huh, that didn't taste like much."

"Thank you both, really," Hanji says. She collects the vials from Armin and Eren, then pulls one of the room's chairs into a corner and settles into it. Crossing her legs, she pulls a pencil from her high ponytail and sets her gaze on the boys in front of her. "Tell me, how do you feel?"

Armin is the first to respond. "Um, my stomach feels a little hot."

Hanji makes a few scribbles on her clipboard. "You, Eren?"

The brunette shrugs in response. "I don't feel anything."

Hanji scribbles again, then reaches into her pocket to click her stopwatch. She leans back in the chair and crosses her arms this time as well. "Just go on as you would, pretend I'm not here."

"Sure," Eren mumbles, flopping back against the bed to stare at the ceiling.

Armin pulls his knees to his chest and turns to face Eren, his back to Hanji. Resting his chin on his knees, he says, "It's been a while since we've had time to just sit around, hasn't it, Eren?"

"Yeah, you're right," Eren says, turning his head to look at Armin.

Armin is looking down at him through his lashes and he blinks, suddenly startled, feeling his heart speed up. Eren isn't sure why he'd never noticed that Armin's eyelashes matched his hair, and he's also unsure as to why he's suddenly noticing that now.

Eren's attention is then brought to Armin's mouth when the blonde says mildly, "Eren? Is there something on my face?"

Eren shakes his head to clear the fog that is seeming to collect in his mind. It doesn't quite work. "Sorry, Armin, I don't know, my head is starting to feel fuzzy."

Armin licks his lips - Eren's eyes flicker to them - before he says, "Yeah, me too." A few heartbeats later, Armin realizes that his body feels warm and heavy, on top of his fuzziness. He has the irrepressible urge to lie down.

"Eren…," he says, his lips tingling as he speaks, "Can you move over? I really… need to…"

Armin trails off as Eren mumbles an acknowledgement and scoots over, his shirt hitching up to bare a spot of his belly. Armin considers touching the exposed skin, then blushes when he realizes what he just thought. His eyes are still trained to Eren's stomach when the brunette's voice interrupts his thoughts.

"Come on, did you make me move over for no reason?"

Eren feels like he wants to sink into the bed beneath him. It's so soft and comfortable; he had hardly wanted to move when Armin asked him, but he did. And then the blonde didn't.

Armin scrambles clumsily to lie beside Eren; he exhales softly at the sudden pleasure of the softness of the bed. Part of him doesn't understand why he feels so good, and the other part of him doesn't care, because he can feel heat rolling off of the boy next to him in waves. It reminds him of so many years ago, now, when he and Eren used to spend hours lying together, talking of their dreams.

"Do you remember when we used to lay like this, when we were kids?" Armin asks. His voice sounds far away, even to his own ears. He lazily rolls over on to his side, facing Eren.

"Of course," Eren murmurs, also rolling onto his side. Armin's face is flushed; the heavy pink of his cheeks sharply contrasts the blue of his eyes. Eren grins, feeling silly, and reaches out to poke Armin's cheek. "You're blushing."

"Hey," Armin giggles. He swats at Eren's hand but his coordination is off, so he just ends up swiping at air. He does manage to lay his palm against Eren's face and say, "You are too, you know."

"'m not," the brunette says, but makes no move to push Armin's hand away. Armin's hand is gentle and warm, and Eren's never minded his touch anyway. Eren stares ahead at the blonde, whose eyes have slipped closed, and studies his expression. He takes in the way Armin's lashes lay against his cheeks; how his lips part when he takes a breath… and that's where Eren gets stuck, his line of focus narrowing down to Armin's mouth.

He can barely think through the haze that's settled over him, but he's pretty sure that he's never noticed before how often Armin's tongue darts out to wet his lips subconsciously. It's alluring; Eren wants to catch it. He scoots closer to Armin and waits; the blonde's eyes flicker open momentarily when his arm falls away from Eren.

"Eren…?" Armin says as he blinks several times, attempting to dispel the blurriness at the edges of his vision to no avail. He sighs and closes his eyes again; the room feels as if it's spinning around him but, at the same time, he's not dizzy. Eren is so close to him, he feels irrationally excited about it. His tongue touches his lower lip, wetting it compulsively.

Eren leans forward as soon as he does so, smashing his lips to Armin's clumsily. Armin squeaks Eren's name against his mouth even as he shivers, his hand coming up to press against the brunette's chest. Eren backs up suddenly, apologies spilling from his lips frantically.

"I'm sorry, Armin, I have no idea what that was, I —"

"It's okay, Eren," Armin interjects, looking at Eren through heavy lashes. "I…,"

Armin pauses, trying to sort through his haziness and find the right words. In the end, he gets impatient with himself and settles on, "I liked it."

The words barely leave his mouth before Eren's mouth is on his again. It's messy, with neither of them having any experience, but that doesn't stop Armin from trying to get closer to Eren, tangling their legs together. Eren is gasping, barely giving either of them time to breath between kisses, his fingers clutching Armin's hips and pulling them flush together.

Armin breaks away when he can't take it anymore, desperately needing to breathe, and Eren breathes his name on a shaky exhale. The smothered feeling fades away from Armin, giving way to two realizations: that he was trembling; and that his cock was throbbing, hot and heavy in his pants, and pressing right up against Eren's.

He looks up at Eren then, a jolt of dizzy arousal traveling through him when they lock gazes. Armin feels feverish when he presses his lips to Eren's again, and he makes a noise that makes him blush, even though he can't help it.

Eren reacts to that, his hips jerking forward to rub against Armin. "I don't know why," the brunette says, pulling away from Armin just to bury his face in his neck, "but everything about you is driving me crazy right now."

"Eren…," Armin sighs, shuddering. He tilts his head away from Eren, instinctively exposing his throat to him. Armin knows why, but he's in no position to care. He rocks against Eren when Eren's tongue drags wetly across his throat, followed by soft suction. Up comes another moan that Armin can't swallow down, his free hand clutching Eren's upper arm.

Eren groans against his neck and says, "I had no idea you would sound like this."

He feels the vibration of Armin's throat against his lips when the blonde responds, somewhat shyly, "I don't mean to…"

Eren's breath puffs out in a laugh. "It's not bad," he says, pressing more kisses to Armin's neck.

Armin cups the back of Eren's neck and runs his fingers through the hair at his nape. "Come back up here," he says. Eren obliges him and Armin kisses him again, thrilled with the tingling sensation that comes every time his mouth touches Eren's.

He doesn't bother to hide his gasp when Eren's hand leaves his hip to wiggle between them, press against his crotch and squeeze. He feels so hot, like he could melt at any instant, and it only intensifies when Eren's hand goes back to his hip to hold him still as he rubs their clothed cocks together. Armin grinds himself against that touch, his fingers tightening in Eren's hair.

Eren moans as his hips jerk against Armin's. "Go ahead, pull," he urges, pressing his head back against Armin's hand. So Armin does, just a tug at first. He loses his breath at Eren's sudden gasp, the way he twitches against him, and the raspy tone to his voice when he murmurs, "Again."

Armin tugs on his hair again, firmly, and Eren's eyelashes flutter with a low moan. He's entranced by how Eren is right now; mouth slack, blushing pink all the way down his neck. Armin feels a fleeting moment of possessiveness and he pulls on Eren's hair once more, harder than before, and Eren's fingers dig into his side.

"Armin," the brunette moans, his hips rocking helplessly as his orgasm comes on him abruptly. Waves of heat and pleasure pulse through him and he rides it out as long he can, desperately grinding himself against Armin.

Armin comes shortly after, scratching blunt nails against Eren's scalp. It takes several moments for his breath to come back to him. He opens his eyes, having not realized he closed them. Eren's eyes are barely open, but Armin can tell the brunette is watching him. He feels like jelly and his head is still fuzzy, so he can't quite read the expression on Eren's face.

He settles down and decides not to worry about it, however, when Eren's arm drapes heavily over his waist. Immediately after, he hears a familiar soft snort of sleepiness. Armin lets himself doze off next to Eren, and doesn't hear Hanji's footsteps as she quietly exits the room.


	2. solo Hanji

Hanji manages to return to her own office in record timing, she thinks. "Wow, just wow," she mutters excitedly to herself, locking her door. She hadn't expected that kind of reaction to her elixir, and now… and now…

Hanji travels around her desk and flops into her plush office chair, one of the few luxuries she has and enjoys. Her mostly blank clipboard clatters to the desk. Hanji's eyes had been glued to Eren and Armin as the results of her experiment had unfolded in front of her. Hanji had been able to observe each side effect - raised temperature, dizziness, flushed skin, lowered inhibitions.

Shakily, she undoes the button of her slacks and slips her hand inside. She's not sure how she kept it together long enough to see the test through; by the end her nipples were pressing stiff against her bra and her panties were soaked through. It's still wet there and it's easy for Hanji to slip fingers inside of herself, the heel of her hand pressing against her clit.

With her other hand she pops the first few buttons of her shirt and slides her fingers into her bra. A fresh surge of wetness comes forth when she twists a nipple. No, she had no idea things would turn out quite like that.

The voices of her subordinates echo in her ears as she rocks up against her hand, fingers straining to go deeper inside of her. She's nearly aching with the need for release; she slumps in her chair, splaying her legs wider.

_How long has it been?_ she thinks through the arousal burning its way through her. _Too long._

Twisting her nipple between her thumb and index finger, Hanji sucks her lower lip between her teeth to keep back her moan. She squeezes around her fingers and shudders as she comes, pleasure rolling through her in hot waves.

She relaxes into her chair with a satisfied sigh and smiles.

"Time to deal with the aftermath."


End file.
